<template>
  <div
    class="com-chart"
    ref="course_learn_ref"
    :style="{ width: '100%', height: '100%' }"
  ></div>
</template>

<script>
import homeview from "@/api/homeview";
export default {
  data() {
    return {
      chartInstance: null,
      allData: [], // 服务器返回的数据
      currentPage: 1, // 当前显示的页数
      totalPage: 0, // 一共有多少页
      timerId: null, // 定时器的标识
    };
  },
  mounted() {
    this.initChart();
    this.getData();
    window.addEventListener("resize", this.screenAdapter);
    // 在页面加载完成的时候, 主动进行屏幕的适配
    this.screenAdapter();
  },
  destroyed() {
    clearInterval(this.timerId);
    // 在组件销毁的时候, 需要将监听器取消掉
    window.removeEventListener("resize", this.screenAdapter);
  },
  methods: {
    // 初始化echartInstance对象
    initChart() {
      this.chartInstance = this.$echarts.init(this.$refs.course_learn_ref);
      // 对图表初始化配置的控制
      const initOption = {
        grid: {
          top: "30",
          left: "3%",
          right: "12%",
          bottom: "3%",
          containLabel: true, // 距离是包含坐标轴上的文字
        },
        xAxis: {
          type: "value",
          name: this.$t("CourseLearnNum.xname"),
          nameLocation: "end",
          minInterval: 1,
          axisTick: {
            show: false, // 去除轴下面的刻度
          },
          splitLine: {
            lineStyle: {
              type: "dotted",
              color: "#eee",
            },
          },
        },
        yAxis: {
          type: "category",
          name: this.$t("CourseLearnNum.yname"),
          nameLocation: "end",
          axisTick: {
            show: false,
          },
          axisLabel: {
            formatter: function (params) {
              var val = "";
              if (params.length > 10) {
                //截取6个字
                val = params.substr(0, 10) + "...";
                return val;
              } else {
                return params;
              }
            },
          },
        },
        tooltip: {
          trigger: "axis",
          axisPointer: {
            type: "line",
            z: 0,
            lineStyle: {
              color: "#2D3443",
            },
          },
        },
        series: [
          {
            type: "bar",
            name: this.$t("CourseLearnNum.sname"),
            label: {
              show: true,
              position: "right",
              textStyle: {
                color: "white",
              },
            },
            itemStyle: {
              // 指明颜色渐变的方向
              // 指明不同百分比之下颜色的值
              color: new this.$echarts.graphic.LinearGradient(0, 0, 1, 0, [
                // 百分之0状态之下的颜色值
                {
                  offset: 0,
                  color: "#5ab1ef",
                },
                // 百分之100状态之下的颜色值
                {
                  offset: 1,
                  color: "#b6a2de",
                },
              ]),
            },
          },
        ],
      };
      this.chartInstance.setOption(initOption);
      // 对图表对象进行鼠标事件的监听
      this.chartInstance.on("mouseover", () => {
        clearInterval(this.timerId);
      });
      this.chartInstance.on("mouseout", () => {
        this.startInterval();
      });
    },
    // 获取服务器的数据
    getData() {
      homeview
        .getCourseLearnNum()
        .then((res) => {
          this.allData = res.data;
          // console.log(this.allData)
          // 对数据排序
          this.allData.list.numbers.sort((a, b) => {
            return a - b; // 从小到大的排序
          });
          // 每5个元素显示一页
          this.totalPage =
            this.allData.list.numbers.length % 5 === 0 &&
            this.allData.list.numbers.length != null
              ? this.allData.list.numbers.length / 5
              : this.allData.list.numbers.length / 5 + 1;
          this.updateChart();
          // 启动定时器
          this.startInterval();
        })
        .catch((error) => {
          "error";
        });
    },
    // 更新图表
    updateChart() {
      const start = (this.currentPage - 1) * 5;
      const end = this.currentPage * 5;
      const showDataName = this.allData.list.names.slice(start, end);
      const showDataNum = this.allData.list.numbers.slice(start, end);

      const dataOption = {
        yAxis: {
          data: showDataName,
        },
        series: [
          {
            data: showDataNum,
          },
        ],
      };
      this.chartInstance.setOption(dataOption);
    },
    startInterval() {
      if (this.timerId) {
        clearInterval(this.timerId);
      }
      this.timerId = setInterval(() => {
        this.currentPage++;
        if (this.currentPage > this.totalPage) {
          this.currentPage = 1;
        }
        this.updateChart();
      }, 3000);
    },
    // 当浏览器的大小发生变化的时候, 会调用的方法, 来完成屏幕的适配
    screenAdapter() {
      const titleFontSize =
        (this.$refs.course_learn_ref.offsetWidth / 100) * 2.5;
      // 和分辨率大小相关的配置项
      const adapterOption = {
        tooltip: {
          axisPointer: {
            lineStyle: {
              width: titleFontSize,
            },
          },
        },
        series: [
          {
            barWidth: titleFontSize,
            itemStyle: {
              barBorderRadius: [0, titleFontSize / 2, titleFontSize / 2, 0],
            },
          },
        ],
      };
      this.chartInstance.setOption(adapterOption);
      // 手动的调用图表对象的resize 才能产生效果
      this.chartInstance.resize();
    },
  },
};
</script>

<style lang="less" scoped>
</style>
